**1. Introduction**

Ionic and neutral atomic and molecular beams are very promising for the synthesis of tool-hardening coatings on an industrial scale [1–9]. Diamond is widely used as an abrasive, as an indenter and cutting tool, and as a heat sink in electronic devices, including as a filler in composite highly heat-conducting materials, and its use in microelectronics is promising. Among the methods for obtaining synthetic diamonds and diamond-like coatings, the method of the ion implantation of carbon has certain advantages. According to [10], the ion implantation of carbon into natural diamond crystals leads to internal epitaxial growth without a visible interface between the grown layer and the crystal surface. The layer synthesized by ion implantation has the same high resistance to acids and oxidation in air at 500 ◦C as natural diamond. Neither one is polished with aluminum oxide; both behave the same when lapping on a diamond polishing wheel and when scratching with a diamond needle or a diamond indenter.

The influence of high-fluence ion irradiation by 10–30 keV Ar+, Ne+, N<sup>+</sup>, N2 <sup>+</sup> and C<sup>+</sup> ions at temperatures from 30 to 720 ◦C on the conductivity and microstructure of a polycrystalline diamond surface layer was experimentally studied in [11,12]. The increase in diamond temperature during irradiation leads to ion-induced graphitization at *T*ir > *T*gr ≈ 200 ◦C. The Raman spectra indicate that irradiation with neon and argon ions at temperatures of the diamond more than *T*ir > 500 ◦C leads to the formation of a nanocrystalline graphite layer that increases the resistivity of the irradiated layer. This effect is not observed under irradiation by nitrogen ions. It was found that dynamic annealing at temperatures above 500 ◦C leads to the recrystallization of the diamond only in the case of irradiation

with carbon ions, and irradiation with impurity ions causes graphitization of the ion-modified diamond layer. Under irradiation with carbon ions, the growth and recrystallization of diamond with a thin (~1 nm) graphite-like layer on the surface occurs.

For the processing and restoration of diamond tools, there is an interest in determining the conditions for the graphitization of the diamond surface to a given thickness and controlled surface growth. A soft graphitized layer on the surface of a diamond can facilitate its mechanical polishing and can be used as a sacrificial layer for planarization. There is an interest in surface build-up for resizing and reshaping a unique diamond tool. In both cases, it is important to reduce or at least maintain the surface roughness during processing.

In this work, graphitization with argon ions, which begins at a temperature of >230 ◦C, and the growth of diamond under irradiation with carbon ions at a temperature of >500 ◦C were chosen as the most promising for instrumental application. The effect of high-fluence ion irradiation on the surface morphology was studied by SEM and AFM methods, and the structure of the irradiated layer was studied by Raman spectroscopy and electrical conductivity measurements.
